Desmazeria rigida (L.) Tutin, fern grass. Annual, fibrous–rooted, several—many–stemmed at base (sometimes several plants growing together), cespitose, ascending, in range ca. 15 cm tall; shoots fine–leaved, with basal leaves and cauline leaves; adventitious roots at basal nodes
Stems (culms) cylindric, < 1 mm diameter at nodes, where hidden white and smooth, where exposed internodes inconspicuously striped green and white, glabrous; internodes hollow.
Leaves alternate distichous, simple with sheath; sheath open, margins touching at base, strongly ridged when dry, glabrous, with membranous margins ca. 0.5 mm wide, without lobes (auricles) at top; ligule membranous and continuous with membranous margins of sheath, irregularly cut at top, 2.5—3 mm long, often splitting to base; blade linear, typically in range 20—50+ × ca. 1.5 mm, the widest at base, flat becoming inrolled upward when water–stressed, entire, long–tapered to tip, parallel–veined with slightly raised veins, minutely scabrous along veins especially above midblade.
Inflorescence spikelets, in terminal panicles, panicle in range to 75 × 11—15 mm, of many spikelets, overall strongly flattened vertically and spikelets dense, with the lowest branches having to 8 spikelets decreasing to 1 spikelet per node at the tip, spikelet in range with (3—)5—10 florets (bisexual or terminal floret sterile with only lemma), bracteate, minutely scabrous, lacking awns; sheath of flag leaf at flowering often concealing the lowest portion of panicle, slender blade of flag leaf ascending and often > panicle; rachis conspicuously angled, often conspicuously 3–sided and scabrous along well–defined ridges and minutely puberulent on faces or low ridges, branches alternate distichous, generally 1 per node, stiff, divergent from rachis with green pulvinus in each axil; stalk beneath floret of lateral spikelets < 1 mm long, of terminal spikelet to 3 mm long, 3–ridged.
Spikelet narrowly lanceoloid compressed side–to–side, in range 3—7 mm long, breaking above glumes and between florets; glumes 2, subequal, conspicuously keeled and acute at tip, (1.3—)1.8—2 × 0.8 mm, green with membranous margins, 3–veined with keel minutely scabrous; rachilla strongly flattened, 0.6—0.7 mm long; lemma ovate, ca. 2—2.7 × 0.8 mm, rounded on back, membranous with 5 green veins not converging at tip, glabrous; palea appearing oblong but concave on back, 1.7—2.1 mm long, always < lemma, membranous and 2–veined and 2–keeled, keels green and scabrous above midpoint, acute at tip.
Flower bisexual; perianth (lodicules) 2, to midpoint of ovary, ovoid, ± 0.35 mm long, fleshy at anthesis, colorless, smooth and without hairs; stamens 3, free, becoming exserted within 1 mm from tip of lemma; filaments ca. 0.9 mm long, white; anthers dorsifixed, dithecal, 0.4—0.6 mm long, cream, longitudinally dehiscent; pollen whitish; pistil 1, 1.2—1.4 mm long; ovary superior, obovoid, 0.55—0.6 × 0.3 mm, cream, glabrous, 1–chambered with 1 ovule; styles 2, bases close, colorless, stigmatic above midpoint; stigmas exserted near tip of lemma, featherlike (plumose) with branches ca. 0.2 mm long.
Fruit achene (caryopsis), falling with palea, ellipsoid, 1.4—1.6 × 0.6—0.7 mm, flat on palea side, short–hairy at tip.
A. C. Gibson